1. Field of the Invention
This invention relates to entrance seals for preventing the transference of fluids around elongated members such as pipes at penetration points through walls. The present bulkhead or penetration seal, which I refer to as a testable bulkhead, may be pressure tested at the initial installation or at any time thereafter to ascertain the integrity of the seal.
2. Description of the Prior Art
The most relevant sealed bulkheads or penetration seals appear to be found in the prior art pertaining to chemical storage and particularly fuel storage and piped fuel distribution systems such as are commonly found at gas or service stations. The majority of underground fuel tanks have a manhole which is accessible from the ground surface through a manhole cover. Fuel lines, as well as electrical conduits typically pass through the wall of the manhole for the purpose of connecting equipment within the manhole to equipment outside of the manhole. Since the manhole and pipes are located underground, there is always the risk of ground water leaking into the manhole around the pipes at the penetration points. Leakage of water into the manhole is undesirable since it could damage equipment such as fuel leak sensors and pumps within the manhole. Leakage of fuel out of the pipeline and the manhole at the wall junction is also not desired for environmental reasons. In modern installations, to avoid fuel leakage from the pipeline, a secondary containment system is used around the primary fuel pipe(s). If a leak occurs in the primary pipe, the fuel is directed by gravity back through a secondary containment pipe into the manhole, where the manhole serves as an emergency reservoir, and where electronic sensors and alarms register the malfunction. However, there is still the possibility that the fuel could accumulate sufficiently within the manhole to reach the junction of the pipe wall penetration, and therefore measures must be taken to contain the accumulated fuel since leakage into the surrounding soil is environmentally unsound and against government regulations.
Various techniques have been used to seal around pipes passing through the wall of the manhole, including welding of the pipes to the chamber wall, and using flanged fittings and sealing gaskets bolted to the wall. Rigidly welding the fuel line or entrance fitting to the chamber wall is not an ideal arrangement since ground shifting often occurs which could rupture the weld or pipe. Simple gasket seals have often failed in the past, with the seals often previously being in an undetectable weakened state for some time prior to the failure. Simple gasket seals, as well as welded connections do not allow for testing of the integrity of the seal at the time of installation or at periodic intervals after installation, and so the sealing connection may be defective at the time of the initial installation.
Therefore, there is a need for a penetration seal which can be tested to determine the integrity of the seal, and for a testable seal that also allows shifting or angling of the pipe at the point of penetration through a wall, and there is no similarly structured prior art which teaches such an arrangement as does the present invention.